Makelore 2.0 initial clean snapshot

src/lib/host-events.ts

@@ -0,0 +1,67 @@
+import { createHostEventSource } from './host-api';
+
+let eventSource: EventSource | null = null;
+
+const HOST_EVENT_TO_IPC_CHANNEL: Record<string, string> = {
+  'opencode:status': 'opencode:status',
+  'opencode:stderr': 'opencode:stderr',
+  'oauth:code': 'oauth:code',
+  'oauth:success': 'oauth:success',
+  'oauth:error': 'oauth:error',
+};
+
+function getEventSource(): EventSource {
+  if (!eventSource) {
+    eventSource = createHostEventSource();
+  }
+  return eventSource;
+}
+
+function allowSseFallback(): boolean {
+  try {
+    return window.localStorage.getItem('niancode:allow-sse-fallback') === '1';
+  } catch {
+    return false;
+  }
+}
+
+export function subscribeHostEvent<T = unknown>(
+  eventName: string,
+  handler: (payload: T) => void,
+): () => void {
+  const ipc = window.electron?.ipcRenderer;
+  const ipcChannel = HOST_EVENT_TO_IPC_CHANNEL[eventName];
+  if (ipcChannel && ipc?.on && ipc?.off) {
+    const listener = (payload: unknown) => {
+      handler(payload as T);
+    };
+    // preload's `on()` wraps the callback in an internal subscription function
+    // and returns a cleanup function that removes that exact wrapper.  We MUST
+    // use the returned cleanup rather than calling `off(channel, listener)`,
+    // because `listener` !== the internal wrapper and removeListener would be
+    // a no-op, leaking the subscription.
+    const unsubscribe = ipc.on(ipcChannel, listener);
+    if (typeof unsubscribe === 'function') {
+      return unsubscribe;
+    }
+    // Fallback for environments where on() doesn't return cleanup
+    return () => {
+      ipc.off(ipcChannel, listener);
+    };
+  }
+
+  if (!allowSseFallback()) {
+    console.warn(`[host-events] no IPC mapping for event "${eventName}", SSE fallback disabled`);
+    return () => {};
+  }
+
+  const source = getEventSource();
+  const listener = (event: Event) => {
+    const payload = JSON.parse((event as MessageEvent).data) as T;
+    handler(payload);
+  };
+  source.addEventListener(eventName, listener);
+  return () => {
+    source.removeEventListener(eventName, listener);
+  };
+}